Jump to content

Petrol lawnmower help


Wasabi
 Share

Recommended Posts

So I have a Briggs and Stratton 148cc lawnmower which has been going strong for over ten years. Last week I noticed it was making a strange noise and was taking longer to start. Today I got it out and it started but only revved at very low revs for about a minute before cutting out. I checked the fuel filter, carb jet, air filter and spark plug before noticing the head gasket had gone round one of the bolts. I took the head off and replaced the gasket.

 

It still won't start. It fires but then idles at very low revs regardless of throttle position and then cuts out after a minute or so. The oil looks really black and it seems to be blowing out the crank breather pipe.

 

Any ideas?

Link to comment
Share on other sites

Try putting carb in a ultra sonic cleaner filled with gunk works great but don't tell the wife I used her jewellery cleaner took me ages to get rid of the smell of the gunk engine cleaner she would kill me if she ever finds out

Edited by chris1961
Link to comment
Share on other sites

I've had cars sat longer than a few months and they started and ran ok on the fuel that had sat in the tank. Must have been lucky with the amount that it kept ok.

 

All my garden tools are ran on aspen2 so I don't get the fuel problems.

Link to comment
Share on other sites

It might be possible that you have lost/unhooked the carb/governor control spring that hooks in a small hole in the top of the butterfly spindle to a fixed bracket at the front under the air cleaner. This spring counters the governor and controls the running speed. It is quite often knocked off if the m/c has been rodded under bushes. Check operation by using finger on throttle butterfly shaft to see if it returns to position. This is a common cause of this problem

Edited by fortune
Link to comment
Share on other sites

Two Replies above have the answer..

Gauze filter,jets dodgy..

Bought an Ultrasonic cleaner,Fired first time,mate had the same problem with his hedge trimmer.

Fires up first pull,worth every penny for the cleaner..

PS.... Check your fuel pipes,slightest bit of air getting in,you can pull till next Christmas..

Link to comment
Share on other sites

What is the diaphragm and where do I find it?

If it's a classic engine with the carb screwed direct to the petrol tank then the diaphragm sits under the carb. There are 2 bits, the gasket and the diaphragm; the diaphragm must sit on the tank.

Sometimes,it's worth replacing the whole carb. Diaphragm kit is about £6 and carb is about 14 which comes with diaphragm.

Link to comment
Share on other sites

If it's a classic engine with the carb screwed direct to the petrol tank then the diaphragm sits under the carb. There are 2 bits, the gasket and the diaphragm; the diaphragm must sit on the tank.

Sometimes,it's worth replacing the whole carb. Diaphragm kit is about £6 and carb is about 14 which comes with diaphragm.

Ah right. The carb is on the side of the engine, below the air intake.

Link to comment
Share on other sites

If the carb does not sit on a metal tank then the chances are it has a float (does the carb have a bowl under it) rather than a diaphragm. If this is the case, an sonic cleaner or solvent bath are in order. It moght also be worth checking the compression, less than 80psi might indicate ring problems or valve clearances need checking.

But fuel or governer seem most likely.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...